Fight Aging!

The balance of microbial populations making up the gut microbiome changes for the worse with aging. Populations that provoke inflammation increase in size at the expense of populations that manufacture beneficial metabolites. We have some idea of the size of the resulting contribution to degenerative aging as a result of fecal microbiota transplantation studies, from young donor to old recipient, carried out in killifish and mice. Old recipients provided with a young gut microbiome composition exhibit improved health and extended life.

Sustained programs of exercise are known to improve the composition of the gut microbiome, reducing the magnitude of some of the changes known to occur with age. This may be the result of improved immune function, and thus a greater ability of the immune system to remove unwanted, inflammatory microbes. It is thought that some fraction of the well-known reduced risk of age-related disease and mortality resulting from exercise may be due to an improved gut microbiome. The question, as usual, is how large a fraction.

In today's open access paper, researchers report on a study of exercise conducted in aged mice with the aim of obtaining potentially illuminating data on the relationship between exercise, health, and gut microbiome composition. The most interesting result is not the health benefits, which are expected, but rather that exercise becomes progressively less effective in altering the gut microbiome as the animals become older.

Age-dependent effects of exercise on gut microbiota-mitochondria axis and cognitive function in aging mice

Aging is accompanied by progressive impairments in mitochondrial bioenergetics, apoptosis regulation, and gut microbiota homeostasis, all of which contribute to cognitive decline. In this study, we investigated whether the effects of treadmill exercise on the gut microbiota-mitochondrion-neuronal plasticity axis differed between young (15 months) and old (28 months) mice. Male C57BL/6 mice were randomly assigned to the following groups: early sedentary, early exercise, late sedentary, or late exercise groups and completed an 8-week treadmill training protocol.

Cognitive function was assessed using the passive avoidance test and the Morris water maze test. Hippocampal mitochondrial respiration, Ca2+ retention capacity, and Bax/Bcl-2 expression were quantified, and the gut microbiota composition was analyzed using 16S ribosomal RNA sequencing.

Mice that did not exercise in old age exhibited memory impairment, decreased mitochondrial oxidative respiration, reduced Ca2+ retention, increased Bax expression, decreased Bcl-2 levels, and decreased abundance of Lactobacillus, Bifidobacterium, and Akkermansia. Exercise significantly improved behavioral performance, mitochondrial function, and apoptosis balance, while also increasing beneficial gut microbiota.

Notably, these effects were significantly greater in late-aged compared to early-aged mice. These results demonstrate that the efficacy of exercise in modulating the microbiota-mitochondrion-brain axis varies with age. Early-aged appears to represent a more responsive biological period during which exercise is more effective in improving mitochondrial integrity, microbiota composition, and cognitive resilience. These results suggest that initiating exercise early in the aging process may maximize neuroprotective effects and delay age-related functional decline.

The protein α-synuclein can misfold into a pathological form and then spread from cell to cell in the central nervous system. This occurs in everyone to some degree with age, but only some people experience a burden of α-synclein pathology large enough to lead to Parkinson's disease or other synucleinopathies. It is likely that everyone exhibits some loss of function due to α-synuclein, but as ever, it is hard to pin down exactly how much of each aspect of aging is due to any one specific mechanism. The only efficient way to obtain useful data is to fix that one specific problem and observe the outcome, which is what researchers did here in aged rats. A gene therapy produced intracellular antibodies that reduce α-synuclein levels, albeit perhaps not in the expected way, and the result is improved function in treated animals.

Abnormal accumulation of alpha-synuclein (αSyn) in axons and presynaptic terminals plays a critical role in αSyn-mediated dopaminergic neurodegeneration. A strong correlation between aging and elevated αSyn levels in the substantia nigra has been identified in both humans and non-human primates. This study aimed to investigate whether AAV-mediated NAC32 intrabody expression in the substantia nigra could ameliorate αSyn-associated dopaminergic dysfunction and improve age-related motor deficits in aged rats.

We first investigated the mechanism by which NAC32 reduces αSyn levels. Comparisons of αSyn burden, tyrosine hydroxylase (TH) expression, and locomotor activity were made between young and aged rats. In aged rats, we evaluated behavioral performance, dopaminergic markers, and synaptic markers following AAV1-NAC32 gene delivery into the substantia nigra. Our results showed that the NAC32-mediated αSyn reduction was not prevented by inhibition of proteasomal, lysosomal, or autophagic pathways and was associated with reduced αSyn mRNA levels.

Aged rats exhibited decreased locomotor activity, elevated αSyn levels, and reduced TH expression in the substantia nigra. NAC32 intrabody expression in the substantia nigra significantly reduced αSyn accumulation, restored TH expression, increased synaptic markers and striatal dopamine levels, and improved locomotor performance in aged rats. These effects occurred without detectable elevation of pro-inflammatory cytokine levels in bulk striatal tissue. Our findings suggest that AAV-mediated NAC32 intrabody expression in the substantia nigra may serve as a therapeutic strategy to mitigate αSyn-induced dopaminergic dysfunction and motor impairments associated with aging.

Link: https://doi.org/10.1038/s41598-025-34908-1

Researchers here review the evidence for chronic inflammation to contribute to the vascular dysfunction of hypertension, in which blood pressure increases to harmful levels. The particular focus is on the feedback loop in which inflammatory immune dysfunction contributes to dysfunction in the regulation of hematopoiesis, the manufacture of new immune cells by hematopoietic cells resident in bone marrow, which in turn causes greater inflammatory immune dysfunction. Sustained inflammatory signaling is harmful to tissue structure and function throughout the body, including the vasculature and systems that regulate blood pressure.

Hypertension is a highly prevalent chronic disease all around the world, and the pathogenic mechanism is complicated. The early and rapid decline of the function of human vascular system due to the aging of human body are characteristics of hypertension, which is accompanied by progressive pathological remodeling and arterial stiffening.

The pathogenetic action of oxidation and inflammation is the vital function in the process of endothelial dysfunction and arterial injury. Bone marrow is considered as the birthplace of the immune cell, and the role of bone marrow in hematopoiesis and immune response for the onset of hypertension has been confirmed. In turn, inflammatory and oxidative stress also affect the bone marrow and damage bone marrow function, causing a series of complications in hypertension, resulting in a vicious cycle. Recently, increasing evidence has suggested that bone marrow aging plays an important role in the onset and development of hypertension, and that the function of bone marrow in the pathogenesis of hypertension has been seriously overlooked. Bone marrow microvascular ageing is also involved in the progression of bone marrow ageing.

Thus, this review mainly focuses on bone marrow function in aging and hypertension progression, addresses the current studies on the roles of vascular aging, the bone marrow and the immune system in hypertension, and discusses their interaction and function in the pathogenesis of hypertension. Furthermore, some novel molecular pathological mechanisms are surveyed. This can add a new impetus to the mechanism research of hypertension onset.

Link: https://doi.org/10.1038/s41420-025-02851-9

The proteasome is a specialized protein complex that breaks down unwanted proteins into short peptide molecules for reuse in further protein synthesis. Any protein designated as unwanted by the addition of a ubiquitin tag can be broken down in this way. This activity is important, a form of cellular maintenance. When impaired, loss of proteasomal function allows damaged and damaging proteins to build up in the cell, degrading the function of other cellular components and activities. Unfortunately, aging causes loss of proteasomal function just as it degrades the function of all complex systems in the cell.

In today's open access paper, researchers discuss the link between the age-related impairment of proteasomal function and the chronic inflammation that is characteristic of aging. This is a part of the increased attention given to the cGAS-STING pathway and its relevance in aged tissues. The sensor cGAS evolved to detect nucleic acids characteristic of invading pathogens, but is unfortunately also triggered by mislocalized DNA from the cell nucleus or mitochondria that escapes into the cytoplasm of the cell. cGAS in turn activates STING, a central inflammatory regulatory. Diminished proteasomal activity allows the build up of misfolded and other harmful proteins that can disrupt mitochondrial function and structure sufficiently to allow mitochondrial DNA into the cell cytosol.

This sort of connection is why interventions that improve forms of cell maintenance such as proteasomal activity and autophagy tend to reduce age-related inflammation. These forms of intervention range from exercise to sophisticated genetic upregulation or downregulation of specific protein machinery used in cell maintenance processes. Some are more practical than others, and effect sizes vary. What they all have in common is that they help to reduce the level of damage in the form of broken proteins inside cells, thereby improving mitochondrial function, and reducing cGAS-STING activity and consequent inflammatory signaling.

Impaired Proteasome as a Catalyst for cGAS-STING Activation in Alzheimer's Disease

Misfolded proteins and protein degradation systems have contributed significantly to the understanding of Alzheimer's disease (AD). The ubiquitin-proteasome system (UPS), is vital for clearing abnormal proteins that could trigger inflammation if accumulated. Neurons are particularly vulnerable to UPS impairment due to their high reliance on precise protein homeostasis for function and survival. Findings from the studies of the 5×FAD and tau-P301S mice revealed that the synaptic proteasome function is impaired even in the early stages, a phase before overt plaque formation, correlating with early memory deficits. Blocking proteasome function in healthy neurons causes AD-like effects, such as oxidative stress, synaptic loss, and cognitive decline.

Conversely, boosting UPS activity can reverse these effects. Deletion of a 26S proteasome subunit causes neurodegeneration and Lewy-like inclusions, accompanied by abnormal mitochondria, linking proteasome failure to mitochondrial dysfunction and neuronal damage that extends beyond protein aggregation. Increased production of reactive oxygen species (ROS) can damage mitochondrial lipids and proteins, compromise membrane integrity, and ultimately cause membrane rupture. This occurs due to abnormal protein aggregation caused by proteasomal failure, which disrupts redox balance. Although UPS is involved in mitochondrial quality control, its impairment weakens the removal of damaged mitochondrial proteins, leading to oxidative stress that eventually causes mitochondrial membrane collapse. This collapse can then leak mitochondrial DNA into the cytosol. This leaked mtDNA acts as a damage-associated molecular pattern, thereby activating the cyclic GMP-AMP synthase (cGAS) and stimulator of interferon genes (STING) DNA-sensing pathway, to cause neuroinflammation.

It has been shown in a neuron-specific proteasome knockout mouse that the cGAS-STING pathway was activated, as evidenced by increased protein levels of cGAS and STING, and pro-inflammatory factors, such as STAT1, NF-κB, IL-1β, TNF-α, and IL-6, as well as signs of neurodegeneration, including decreased brain weight and necroptosis markers. These results link proteasomal dysfunction to immune responses and cell death in the brain

Researchers here conduct a meta-analysis of clinical trial results for the effects of resistance exercise on cognitive function. As might be expected given what is known of the effects of exercise on health, the amassed data strongly indicates that programs of resistance exercise improve cognitive function in older people. Mechanistically, it is known that exercise reduces inflammation, increases blood flow to the brain, improves immune function, improves mitochondrial function, increases autophagy, and touches on a range of downstream effects of those changes that may positively impact the state of the aging brain.

Resistance exercise has recently gained attention as a promising strategy to promote neuroplasticity and mitigate cognitive deterioration; however, evidence from randomized controlled trials (RCTs) remains inconsistent. This systematic review and meta-analysis aimed to evaluate the effects of resistance exercise on cognitive function in older adults.

17 RCTs (n=739) met the inclusion criteria. Pooled analyses showed that resistance training significantly improved overall cognitive function (standardized mean difference, SMD = 0.40), working memory (SMD = 0.44), verbal learning and memory (mean difference, MD = 3.01), and spatial memory span (SMD = 0.63), whereas effects on processing speed, executive function, and attention were not significant. Heterogeneity and publication bias analyses indicated stable and unbiased results. The magnitude of improvement appears to depend on age and exercise parameters, suggesting a potential dose-response relationship.

Link: https://doi.org/10.3389/fpsyt.2025.1708244

Researchers here provide data to support the claim that if everyone had the most favorable ε2 variant of the APOE gene, Alzheimer's disease incidence would be a tenth of what it is now. APOE is involved in cholesterol trafficking and metabolism, and in recent years it has been suggested that the APOE variants connected with higher risk of Alzheimer's cause dysfunction in microglia in the brain. Independently, that microglia become more inflammatory and dysfunctional with age has become an important line of research in the study of neurodegenerative conditions. Evidence strongly supports an important role for dysfunctional microglia in provoking the pathology associated with these conditions. Therapies focused on microglia have yet to emerge, but a number of approaches demonstrated in the laboratory and animal studies could lead to clinical trials given sufficient motivation and funding.

Variation in the APOE gene strongly affects Alzheimer's disease (AD) risk. However, the proportion of AD burden attributable to this variation requires clarification, which would help to elucidate the scope of strategies targeting apolipoprotein E (APOE) for AD prevention and treatment. We estimated the extents to which clinically diagnosed AD, AD neuropathology and all-cause dementia are attributable to the common APOE alleles in four large studies.

First, we used data on 171,105 and 289,150 participants aged ≥60 years from UK Biobank (UKB) and FinnGen, respectively. AD and all-cause dementia were ascertained from linked electronic health records in these cohorts. Second, we examined amyloid-β positivity from amyloid positron emission tomography scans of 4,415 participants of the A4 Study. Third, we analysed data from the Alzheimer's Disease Genetics Consortium (ADGC), where neuropathologically confirmed AD cases were compared to pathology-negative, cognitively intact controls (N = 5,007).

In each analysis, we estimated outcome risk among carriers of APOE risk alleles ε3 and ε4, relative to individuals with an ε2/ε2 genotype, and calculated attributable fractions to show the proportions of the outcomes due to ε3 and ε4. For AD, fractions ranged from 71.5% in FinnGen to 92.7% in the ADGC. In A4, 85.4% of cerebral amyloidosis was attributable to ε3 and ε4. The proportions of all-cause dementia attributable to ε3 and ε4 in UKB and FinnGen were 44.4% and 45.6%, respectively. Without strong underlying risks from APOE ε3 and ε4, almost all AD and half of all dementia would not occur. Intervening on APOE should be prioritised to facilitate dementia prevention.

Link: https://doi.org/10.1038/s44400-025-00045-9

The thymus is a small inner organ near the heart that is responsible for the maturation of T cells of the adaptive immune system. The supply of new T cells is critical to the maintenance of effective immune function over time. Unfortunately the thymus atrophies over the course of adult life, and in most people is largely made up of inactive fat tissue by as early as 50 years of age. The resulting diminished supply of replacement cells ensures that the T cell population thereafter becomes ever more made up of malfunctioning, exhausted, and senescent cells incapable of mounting an effective response.

Given the pressing need for ways to restore lost immune function in older individuals, it is good to see that a fair number of biotech startup companies are now competing to develop means of regenerating the aged thymus. After something of an abandonment of efforts following 2010s work on FOXN1 as a regulator of thymic growth, the past few years have seen a number of programs make the leap from academia to industry. Hopefully one or more will result in a form of therapy that is both effective and cost-effective.

The primary challenge presented by the thymus is targeted delivery of therapeutics. Quite a few approaches are known to kickstart the thymus into regrowth of the active regions of tissue capable of nurturing new T cells. Unfortunately they all produce serious side-effects in other tissues when delivered at sufficient high systemic doses to ensure that enough of the therapeutic make it to the thymus. For example, delivery of recombinant keratinocyte growth factor (KGF) reliably regrows the thymus in aged mice and non-human primates. There is a human drug based on KGF, used sparingly for some complications of cancer therapy. Dosing with this drug at levels sufficient to regrow the human thymus would result in very unpleasant complications, sufficiently serious to disqualify its use in this context.

There are as yet no robustly demonstrated ways to target therapies to the thymus other than direct injection, a procedure that carries sufficient cost and risk to make it infeasible for widespread use in older individuals. Thus while the new biotech startup noted in today's article is working on a growth factor approach for thymic regeneration, in reality that means that they are working on some combination of delivery system and therapy that can limit the effects of growth factors to the target thymic tissue. That is the core challenge, delivery.

Thymus regeneration startup emerges to 'restore immune function'

Swiss biotech TECregen emerged today with seed financing to develop a pipeline of therapies designed to regenerate the thymus and boost the aging immune system. The company is built around the idea that restoring the thymus can restore immune function at its source. The gradual loss of thymic function is increasingly viewed as a biological bottleneck for healthy aging. A shrinking thymus contributes to weaker responses to vaccines, slower recovery from infections and diminished immune surveillance against emerging cancers.

TECregen is developing a class of biologic drugs it calls thymopoietics, engineered to regenerate thymic epithelial cells and rebuild the microenvironment required for effective T-cell production. Thymic epithelial cells are the structural and functional backbone of the thymus; without them, T cells cannot mature properly. By rejuvenating this cellular niche, TECregen aims to restart the production of healthy, diverse T cells and restore immune resilience across a range of conditions, from immune aging to cancer-related immune suppression.

The basis of TECregen's approach involves applying advanced ligand engineering to growth factor biology. Growth factors are potent signaling molecules that influence inflammation, tissue repair, and regeneration, including processes within the thymus. According to the company, historic attempts to use growth factors therapeutically have been hampered by systemic toxicity and poor tissue selectivity, as these molecules can trigger unwanted effects in multiple organs. TECregen aims to engineer these signals to be functionally selective and tissue-targeted, with the goal of concentrating their activity in the thymus while minimizing off-target effects.

Cells become senescent constantly throughout the body and throughout life, near all as the result of reaching the Hayflick limit on replication, but also due to excessive cell stress, damage, or a toxic environment. A senescent cell ceases replication, enlarges, and secretes a pro-inflammatory, pro-growth mix of signals that attracts the attention of the immune system. In youth senescent cells are efficiently destroyed by the immune system, but this clearance slows down with age. Senescent cells thus accumulate in later life to cause chronic inflammation and disruption to tissue structure and function. The immune system also accumulates senescent cells, and researchers here investigate the epigenetic regulation of gene expression in these cells, with an eye to finding ways to reduce the burden of senescence in these populations.

The age-associated accumulation of senescent cells in tissues is one of the driving causes of aging and age-related disease. Although senescent cells secrete chemokines that facilitate the recruitment of cytotoxic immune cells for their elimination, senescent cells accumulate systemically with advancing age, suggesting that immune cell-mediated elimination of senescent cells becomes impaired with age. Recent evidence highlights a dysfunctional adaptive immune system as a potential cause for the age-associated accumulation in senescent cells. In older humans, both CD4+ and CD8+ T cells acquire features of senescence, which is linked to defective immune responses. However, the gene regulatory mechanisms that promote senescence of CD8+ T cells in aging humans, as well as the contribution of senescent CD8+ T cells to disease, remain poorly understood.

We defined and validated the transcription factor (TF) networks that control the senescence program in CD8+ T cells of a cohort of younger and older donors. One key finding of our study is that the acquisition of senescence is the main driver of epigenomic and gene expression dynamics of CD8+ T cells, with a minor contribution of chronological age. The transition to the senescence state is a major event in the epigenetic life of CD8+ T cells, as it involves the differential expression of 40% of all detectable TFs. Inhibition or downregulation of AP1, KLF5, or RUNX2 modulates the transcriptional output and partially restores the blunted response to stimulation of senescent CD8+ T cells.

Link: https://doi.org/10.1016/j.celrep.2025.116795

Much of the research into TGF-β signaling show that raised circulating levels of TGF-β drive chronic inflammation and related dysfunctions. Researchers have shown that reducing TGF-β levels can be used to improve health and extend life in mice, for example. Yet nothing is simple and straightforward when it comes to cellular biochemistry. Here, researchers provide evidence for a beneficial function of TGF-β, in that its presence restrains the inflammatory activity of the innate immune cells known as microglia to better preserve myelin structure in the aged spinal cord.

Microglia survey and regulate central nervous system myelination during embryonic development and adult homeostasis. However, whether microglia-myelin interactions are spatiotemporally regulated remains unexplored. Here, by examining spinal cord white matter tracts in mice, we determined that myelin degeneration was particularly prominent in the dorsal column (DC) during normal aging. This was accompanied by molecular and functional changes in DC microglia as well as an upregulation of transforming growth factor beta (TGF)β signaling.

Disrupting TGFβ signaling in microglia led to unrestrained microglial responses and myelin loss in the DC, accompanied by neurological deficits exacerbated with aging. Single-nucleus RNA-sequencing analyses revealed the emergence of a TGFβ signaling-sensitive microglial subset and a disease-associated oligodendrocyte subset, both of which were spatially restricted to the DC. We further discovered that microglia rely on a TGFβ autocrine mechanism to prevent damage of myelin in the DC. These findings demonstrate that TGFβ signaling is crucial for maintaining microglial resilience to myelin degeneration in the DC during aging. This highlights a previously unresolved checkpoint mechanism of TGFβ signaling with regional specificity and spatially restricted microglia-oligodendrocyte interactions.

Link: https://doi.org/10.1038/s41593-025-02161-4

The article I'll point out today manages to capture much of the gist of the present state of interactions between two opposing viewpoints on aging: firstly that aging is the consequence of an accumulation of cell and tissue damage, a byproduct of evolutionary focus on early life success, and secondly that aging is an evolved program in its entirety. In essence, the trend is now towards some form of synthesis of these two viewpoints, that the panoply of mechanisms making up degenerative aging contain something of both stochastic damage and programmed functions. One might look at the present state of the hyperfunction theory of aging as an at times confusing and contradictory effort to produce such a synthesis.

At the time that these views emerged in opposition, it mattered as to which viewpoint governed the direction of research and development aimed at intervening in the aging process. If aging is damage, then identifying and repairing damage is the only viable approach likely to produce sizable gains in health. If aging is a program (that produces damage), then adjusting gene expression and the operation of metabolism is the only viable approach likely to produce sizable gains in health.

One could point to the Strategies for Engineered Negligible Senescence for a clear paradigm of damage repair (and still can, as its component parts have been demonstrated to be useful by the results of animal studies). One could point to efforts to alter epigenetic control over gene expression, and thus the operation of metabolism, as clearly falling into a paradigm of attempts to control an aging program. That division has been muddied by the discovery that DNA double strand break repair produces epigenetic aging, coupled with the development of epigenetic reprogramming as an approach to restoring youthful epigenetic patterns to aged cells. Epigenetic reprogramming would have been called an effort to alter metabolism to adjust the aging program, but thanks to new discoveries can now be thought of as a form of damage repair. The world turns, and matters change.

Why Aging Is Not Fundamentally Programmed - and Why Programming Still Matters

Theories of aging can be broadly categorized into two groups. On one hand are those that think aging is caused by accumulation of damage due to entropy and that solving aging requires repairing these damages. On the other hand are those that think aging is driven by an evolved genetic program whose function is to cause aging. They think the solution to aging is to instruct the body to fix itself by reprogramming its cells.

The latter view has become more popular lately since it was discovered that cells can be reprogrammed to become younger in most aspects, by changing their gene expression. That shift was also amplified because several early "damage theories" were framed as overly narrow single-cause explanations that failed to explain aging (the free radical theory of aging is a classic example). Reprogramming therefore started feeling like a more complete theory. Some scientists think that if we could simply rejuvenate all the cells in the body through reprogramming their gene expression, we could then rejuvenate the whole body and effectively solve aging.

A critical error in modern aging debates is thinking that aging must be caused by either damage accumulation or programming, while in fact, both factors play a strong role in aging. More accurately, aging is fundamentally caused by accumulation of damages, but it is also influenced very strongly by programming. Reprogramming is a highly promising strategy to slow down and reverse aging. The point is, we will never get close to fully reversing aging in humans without addressing damage accumulation also. Reprogramming may partially restore many cells to more youthful states, but it cannot automatically remove a great portion of structural damages such as many of those found in the extracellular matrix.

Why does exercise slow the age-related loss of bone mineral density leading to osteoporosis? Researchers here find a critical role for mechanotransduction, the sensing of physical forces placed upon a cell, such as pressure or mechanical stress. Specifically the mechanosensor Piezo1 is triggered in mesenchymal stem cells in the bone marrow, and the subsequent response of this cell population acts to reduce inflammation, reduce fat cell generation in bone marrow, and thus allow the specialized cell populations working on bone extracellular matrix structures to better maintain a healthy bone mineral density. This opens the door to the development of therapies that can mimic this effect of exercise by triggering Piezo1 or downstream pathways.

With aging or osteoporosis, bone marrow adipogenesis is increased and inversely correlates with the loss of bone mass. Bone marrow adipocytes are derived from multipotent bone marrow mesenchymal stem cells (BMMSCs), which can differentiate into either fat or bone. BMMSCs are mechanosensitive cells, but how mechanical loading is implicated in the in vivo regulation of bone marrow adipogenesis and its impact on bone remodeling remain poorly understood. Here, we identify the mechanosensitive cationic channel Piezo1 in BMMSCs as a key suppressor of bone marrow adipogenesis by preventing local inflammation, thereby enhancing osteoblast differentiation and bone formation.

Importantly, our findings also indicate that Piezo1 invalidation abolishes exercise-induced benefits on bone volume and marrow adiposity, suggesting that Piezo1 senses physiological mechanical stress (presumably shear stress and compressive forces) in the bone marrow to regulate BMMSC fate decision. These findings demonstrate that Piezo1 activation in BMMSCs suppresses bone marrow adipogenesis to maintain bone strength by preventing the Ccl2-Lcn2 inflammatory autocrine loop, thus uncovering a previously unrecognized link between mechanotransduction, inflammation, and cell fate determination.

Link: https://doi.org/10.1038/s41392-025-02455-w

RNA splicing is the assembly of exons (and discarding of introns) to form a protein. Many genes contain the instructions for multiple proteins, and which protein is produced is governed by the operation of the splicing machinery. That operation is known to change with age, but the question remains open as to just how important RNA splicing is to age-related degeneration. Researchers here use a novel approach to identify genes with age-related alterations in expression that are similar in all tissues, and find that the results are biased towards RNA splicing machinery. The interesting part of the paper is the speculation in the discussion section regarding the reasons why alterations in RNA splicing activities could be important in aging, suggesting a connection to DNA damage. This line of thinking is particularly interesting given recent evidence for repeated activation of DNA repair processes to trigger the epigenetic changes characteristic of aging. Looking at DNA damage, epigenetic change, and altered alternative splicing may be three viewpoints into the same process of aging centered on the structure and function of nuclear DNA and its surrounding machineries of gene expression.

Although transcriptomic changes are known to occur with age, the extent to which these are conserved across tissues is unclear. Previous studies have identified little conservation in age-modulated genes in different tissues. Here, we sought to identify common transcriptional changes with age in humans (aged 20 to 70) across tissues using differential network analysis, assuming that differential expression analysis alone cannot detect all changes in the transcriptional landscape that occur in tissues with age. Our results demonstrate that differential connectivity analysis reveals significant transcriptional alterations that are not detected by differential expression analysis. Combining the two analyses, we identified gene sets modulated by age across all tissues that are highly enriched in terms related to "RNA splicing" and "RNA processing".

Alternative splicing is a fundamental process in eukaryotes that allows the same gene to encode multiple different transcripts, with approximately 95% of multi-exon genes producing transcripts that undergo alternative splicing. Therefore, it is intuitive that alterations in the splicing machinery would have systemic effects on the biological network. Indeed, aging appears to be accompanied by a high incidence of aberrant splicing and intron retentions. Changes in alternative splicing are also observed in several age-related diseases. Modulation of specific splicing factors has been shown to increase lifespan in model organisms, and splicing appears to be modulated in model organisms during dietary restriction and mTOR inhibition, two known lifespan-promoting interventions.

Determining the cause of this increased incidence of aberrant splicing is currently impossible. One hint is the presence of genes associated with DNA repair and DNA damage response. The idea that DNA alterations cause aging is one of the most classic theories of aging, and DNA damage is a hallmark of aging. It is possible, therefore, that damage to DNA is leading to aberrant splicing. Indeed, there seems to be a connection between RNA splicing and DNA damage response, even at the transcriptional level.

From the results described here, it is reasonable to imagine a scenario in which the age-associated increase in aberrant mRNAs, proteins, and eventually organelles, which were negatively affected by malfunctioning proteins, may impose significantly on catabolic processes such as RNA catabolism, protein catabolism, and autophagy. Lifespan extension by mTOR inhibition may thus be working by inducing the clearance of these defective components. Since these clearance mechanisms seem upregulated with age, mTOR inhibition is enhancing a naturally occurring attempt at adaptation by the cells.

Link: https://doi.org/10.18632/aging.206347

The composition of the gut microbiome changes with age in ways that harm long-term health, via growth in inflammatory species versus loss of species producing beneficial metabolites. This is well demonstrated in a range of species, including extensive human data. Presently widely available probiotic and prebiotic approaches only produce short-term adjustment in the balance of microbial popultions, but there are a few alternative approaches to adjust the gut microbiome that do produce permanent change with a single course of treatment. One of these is fecal microbiota transplantation. In animal studies, fecal microbiota transplantation from young donors to aged animals rejuvenates the composition of the gut microbiome, improves health, and extends life span.

Data suggests that some age-related conditions are associated with an altered gut microbiome, including Alzheimer's disease and Parkinson's disease. Interestingly, Parkinson's disease includes intestinal symptoms such as constipation that have motivated researchers to conduct some small trials of fecal microbiota transplantation; neurological symptoms of the condition were also improved as a result. Beyond this there is as yet little clinical evidence for effects of fecal microbiota transplantation in the context of aging. More data would be very useful, as this form of therapy is readily conducted, costs little, and certainly could be more widely used than is presently the case given a larger body of supporting evidence.

The application of fecal microbiota transplantation in Parkinson's disease

Parkinson's disease (PD) is a multisystem neurodegenerative disorder characterized by the aggregation of α-synuclein (α-syn) in dopaminergic neurons of the substantia nigra. The pathogenesis of PD remains incompletely understood, and disease-modifying therapies are lacking. Emerging evidence suggests that gut microbiota and their metabolites influence both intestinal and central nervous system (CNS) functions via the microbiota-gut-brain axis (MGBA). Recent studies have identified dysbiosis in the gut microbiota of PD patients, which may contribute to disease progression through two primary mechanisms: First, increased intestinal permeability, allowing pro-inflammatory factors and microbial metabolites to affect the enteric nervous system (ENS) and subsequently spread to the CNS via the vagal neurons; Secondly, disruption of the Blood-Brain barrier (BBB), leading to neuroinflammation and aberrant α-syn aggregation, ultimately resulting in dopaminergic neuron degeneration.

Fecal microbiota transplantation (FMT) has demonstrated significant efficacy in alleviating PD-associated constipation, characterized by an increased abundance of Firmicutes and decreased proportions of Proteobacteria and Bacteroidetes in treated patients. These microbial compositional changes correlate with effective amelioration of both constipation and tremor symptoms. In 2021, a study demonstrated that FMT significantly reduces Bacteroides abundance while increasing Prevotella and Blautia populations in PD patients with constipation. These microbial alterations were associated with marked improvements in PD symptoms. Another group conducted colonoscopic infusion of donor FMT in six PD patients, demonstrating significant improvements in motor symptoms, non-motor symptoms, and constipation over a six-month observation period. In 2024 researchers conducted a nasoduodenal FMT trial involving 43 early-stage PD patients. Post-transplantation assessments revealed significant improvements in both motor symptoms and constipation compared to baseline. Notably, the study also demonstrated FMT-mediated enhancement of cognitive functions, including amelioration of anxiety, depressive symptoms, and sleep disturbances.

Sensors such as cGAS in the cell evolved to detect invading pathogens and then interact with inflammatory regulators such as STING to produce an appropriate response. With age, however, many of the dysfunctions that arise in a cell can produce a maladaptive response on the part of cGAS and STING. The example noted here is the activation of dormant transposons in the genome, a feature of aging that emerges as epigenetic control over the structure of nuclear DNA and expression of nuclear genes changes for the worse. Retrotransposons like LINE-1 make up a sizable fraction of the genome as a result of their ability to copy themselves. They are most likely the remnants of ancient viral infections, important in aging as they become active, and likely important as a source of evolutionary change to genetic sequences as well. Retrotransposons can cause harm not just by damaging the genome as they copy themselves, but also via inflammatory reactions on the part of cGAS, STING, and other mechanisms evolved to react to anything that looks like viral machinery.

Aging is characterized by systemic inflammation and progressive cognitive decline, yet the molecular pathways linking peripheral aging signals to central nervous system dysfunction remain elusive. Here, we identify plasma extracellular vesicle (EV)-derived long interspersed nuclear element-1 (LINE-1) RNA as a potent systemic aging factor mediating neuroinflammation and cognitive impairment in humans and mice.

Plasma EV LINE-1 RNA levels markedly increase with age and strongly correlate with established brain aging biomarkers, including neurofilament light chain (NFL). Utilizing mouse models, we demonstrate that EVs from aged individuals penetrate the blood-brain barrier, deliver LINE-1 RNA to microglia, and initiate cGAS-STING signaling, leading to pronounced neuroinflammation, neuronal damage, and impaired cognition.

Pharmacological blockade of LINE-1 reverse transcription by 3TC or inhibition of STING signaling with H151 significantly ameliorates these age-associated deficits. Notably, aged peripheral tissues, especially brain and lung, emerge as primary sources of pro-aging EVs enriched with LINE-1 RNA, revealing a novel mechanism of inter-organ communication in aging. Our findings position EV-derived LINE-1 RNA and its downstream cGAS-STING pathway as critical systemic drivers of brain aging, presenting promising therapeutic targets for mitigating cognitive decline and age-related neurodegenerative diseases.

Link: https://doi.org/10.1111/acel.70350

Researchers here discuss what is known of the bidirectional relationship between the aging of skeletal muscle and the aging of the gut microbiome. Muscle tissue is metabolically active, generating myokine signals influential on other tissues. This signaling is far from fully mapped, but is known to be important to health, such as via mediating some of the benefits of exercise. Myokine signaling can also affect the composition of the gut microbiome. In turn, changes in the gut microbiome can contribute to the characteristic loss of muscle mass and strength that takes place with advancing age via increased inflammatory signaling or reduced generation of beneficial metabolites known influence muscle metabolism, such as butyrate.

The interplay between gut microbiota and sarcopenia has emerged as a cutting-edge research topic in the medical field, garnering significant attention. Sarcopenia is an age-related syndrome characterized by a progressive decline in skeletal muscle mass, strength, and function, which profoundly impacts the quality of life in older adults and imposes substantial socioeconomic burdens on many counties. Accumulating evidence indicates that alterations in the gut microbiota are not only linked to various intestinal disorders but also to aging-associated conditions, such as sarcopenia.

The gut microbiota plays a pivotal role in regulating skeletal muscle homeostasis via its metabolic products and is increasingly recognized as a potential pathophysiological factor contributing to sarcopenia development. Skeletal muscle, functioning as both a motor and endocrine organ, secretes myokines that exert critical regulatory effects on the gut microbiota. In sarcopenic individuals, reduced secretion of myokines correlates with decreased microbial diversity and compositional shifts, marked by diminished beneficial microbes and increased potentially harmful species. This establishes a vicious cycle of gut dysbiosis-sarcopenia-gut dysbiosis.

Modulation of the gut microbiota has been demonstrated to enhance muscle mass and function in elderly patients with sarcopenia. Metabolites derived from the gut microbiota, such as amino acids, lipopolysaccharides, and short-chain fatty acids, are known to modulate skeletal muscle protein metabolism by influencing anabolic and catabolic pathways. Nevertheless, the bidirectional mechanisms underlying the relationship between gut microbiota and age-related sarcopenia remain incompletely understood.

Link: https://doi.org/10.3389/fmicb.2025.1638880